Print-out emulsions



Patented Feb.13, 194

UNITED STATES T'ENT, o l-Fiend 2,360,449 PRINT-OUT EMULSIONS Y George arranges, ltochesten'N. Y., assignor to Eastman Kodak Company, Rochester. N. Y., a corporation of New Jersey a -No Drawing. Application December 14, 194:; Ndsuass 1 5 Claims.

' inventionfrelates to photo graphic material and more particularly to a photographic emulsion ofthetype known as-print-out emulsions.

Print-out emulsions are characterized by the fact that a visible image is producedin them dia rectly by the action elflight whereas developing -emulsions or developing out emulsions must be subjected to the action ofa developer in order to produce a visible image. The present invention relates to print-out emulsions and especially to those in which the light-sensitive element is a silver. halide.

Print-out emulsions are'usually prepared by the precipitation in a colloidal medium of a he.-

lide of silver by interaction of a solution of a' soluble halide with a solution of alsoluble 'comsions of silver chloride, the silver chloride is usually precipitated inthe colloidal medium in such a way that the final product contains an 39 excess of soluble silver compound, for. instance, silver nitrate; the silver salt of; an organic acid. such as silver citrate or silver tartrate, together with some of the free organic acid. The emulsions are not washed after precipitation .of. the

silver halide; *Print-out emulsions of silver bromide are prepared similarly.

The-sensitivity to light of print-out emulsions maybe'increased by the addition at halogen absorbers such as soluble nitrites, alkaline m'ate-' A typical print-out emulsionjaccording to my my invention, by preparing rials such'as borax, sodium hydroxide, ammonium hydroxide and organic alkalies such as pyridine cramines. o t It is an object of the present invention to pro vide. a diflerent type of print-out emulsion. A'

further object is to provide a means for prepar D 'ing a very fast print-out emulsion. 1 lg ese objects are accomplished; according to a gelatino-silver halide emulsion containing an excess of 'soluble halide and adding to. the emulsion thus prepared sio'n.

invention, was prepared in the following man-- A solution or sea grams of silver nitrates-3m .cc. of water. heated to 60? ,G.-,- .was mixed with asolutioncof 311 gramsofpotas'sium'bromide in\ .2600 cc. of 1.3% gelatinsolution; heated to 60 C. e e I The silver nitrate solution was run into the bro-Q ssprint-out m., m m

pound of silver. In the case of print-out emulmide gelatin solution mac minutes withstirring and the silver bromide was precipitated in the gelatin with an excess of potassium bromide. After'the precipitation 01' the silver bromide, 215 grams of dry gelatin were added to the emulsion.

- A solution of 10 gramsof-thiosalicylic acid dissolved in 600cc. of methyl alcohol and adjusted with ammonium hydroxide to a pH of 6.9 was then added. The emulsion was heated for 30 10 minutes at 60! C. and-was thenchilled to set. v

To finish the emulsion and prepare it for coating, it was washed, melted at 'Q.,' and 100 grams of gelatin were added to it at 70 C. to finish. The emulsion was then ready for. coating.

Th'emulsion thus prepared was coated on a suitable support and dried.- It was then eiposed for 5 minutes on a print-out sensitometer through a power of 2 step tablet by 'a 500 watt lamp 24 step tablet used for this exposure produced 12 steps on the material whereas a similar. exposure got a commercial print-out material produced only '7 steps. This means that the print-out material produced according to my invention was 32 times 1 I 25 as fastas the commercial print-out material with which it was compared.

. The color of the densities produced upon exposure was neutral blue-gray and the color'. of

v the emulsion before exposure was yellowish-white. ao or cream-white, depending upon whetheripotas I usedin=theemulsion forsium iodide hadbeen mula.

The amdunt For jthiosalicyllc ;acid used m 'the example'above was 1 gram of thiosalicylic acid to 35 about '43 grams of silver bromide. The preferred amount'oi' thiosalicyl'c acid is, therefore, "about 2% of the amount of -silver.halide in the emulsion. However, more-or less than this amount can be employed and-the thiosalicyli'c acid con vcentration may vary from about20 mg. to 4000 mg. per grams of silver halide. r

n is to be understood thatthe examples 131d I modifications included herein ustrativeonly and that my invention is to [I claim:

print-out emulsion, which precipitat-. ing a light-sensitive silver halide in 'gelatin'to 50 form anemulsion having an excess- 01' soluble 1,

' halide, and adding to the resulting emulsion from ideof thiosallcylic acid. -2. 'l'heprocess of producing inches from the material. The neutral density a m to only by the scope of'th'e appended ,1. The Process of a light 'sensitiv'e ing a. light-sensitive silver halide in gelatin to form an emulsion having an excess of soluble halide, and adding to the resulting emulsion approximately 2%. by weightof the silver halide of thiosalicylic acid;

3.'The process of producing a, light-sensitive print-out emulsion, which comprises precipitating in gelatin a, light-sensitive silver bromide to form an'emulsion having an excess of soluble bromide, and then adding to the emulsion an amount of thiosalicylic acid which is approximately.2% by weightof the silver bromide.

4. A lightsensitive print-out emulsion comprising a gelatino-silver halide emulsion containing an excess of soluble bromide andtfrom 20 to 4000 milligrams per 50 grams of silver halide oi thiosalicylic acid.

5. A light-sensitive print-out emulsion comprising a gelatino-silver bromide emulsion contaihing an excess of soluble bromide and an amount of thiosalicylic acid which is approxim mately 2% by weight of the silver bromide.

GEORGE E. FALLESEN. 

